Rear Discs or Rear Diff?

[Pool Fixer]

If you had $1500.00 burning a hole in your pocket and time for only one... would you do the dr. diff 10.7 disc kit (since I'll be in the brakes doing the fronts over and this way I'd only be tearing into them one time) and have money left over....... or use the $1500.00 toward a new dr diff or quick performance 3.23 center section. currently have 3.91's and rear drums soaked in gear oil from a leaky axle seal.

I do have the parts in hand for dr diff 13" cobra front kit and a set of new rear shoes with all new hardware. 2 different price points but since I'll be into the brakes already for the fronts, the rear disc option becomes part of the conversation.

I'll also add that this is more of a restomod car with non stock larger wheels and the drums are visually out of place when looking at them through the spokes of 18" wheels.

Both new diff and rear discs will happen eventually, just trying to decide what gets done in the here and now vs a few months away.

 

[Thrashingcows]

As someone who has done rear discs on their 8.75" rear years ago and driven a lot of miles I can honestly say for me it was a waste of money. Do they look cool through my 15x7 cop car rims...sure they do, but do they offer me any real advantage in breaking over the 11x2.5" drums I had on there before...not that I can tell.

Now if you actually road or maybe drag raced and required the better braking then I'd say go ahead but for just cruising they are not worth the investment IMO.

Nice sure grip set of 3.23's....Yes please!

 

[33 IMP]

I'd buy the pumpkin, and just fix the drum brakes.


....but every Mopar I own still has drums all around.

 

[Kern Dog]

As someone who has done rear discs on their 8.75" rear years ago and driven a lot of miles I can honestly say for me it was a waste of money. Do they look cool through my 15x7 cop car rims...sure they do, but do they offer me any real advantage in breaking over the 11x2.5" drums I had on there before...not that I can tell.

Absolutely true.
My car stops NO better with the Dr Diff 11.7" rear discs than it did with 10" rear drums but the discs look better.

 

[fesser]

As someone who has done rear discs on their 8.75" rear years ago and driven a lot of miles I can honestly say for me it was a waste of money. Do they look cool through my 15x7 cop car rims...sure they do, but do they offer me any real advantage in breaking over the 11x2.5" drums I had on there before...not that I can tell

X2 on what T-cows said. Years ago I called Master Power Brakes with the intention of ordering discs for my 12 bolt rear (Chevelle I traded for my R/T). The salesman talked me into running rear drums. The gist of the discussion was that the fronts did something like 70% of the braking work and that drums with good shoes were more than capable of handling the remaining 30%.

 

[diesel_lv]

Unless you are racing on a road course w a lot of turns requiring very frequent hard braking, rear discs do basically "Zero".

 

[Pool Fixer]

F rear discs then! I'm quite impressionable. She looks restomod but it's a cruiser. 3.91's are the last leftover from a time in my life where I just had to go fast. Already ditched the headers, doublepumper carb. I'm hoping the 3.23's are good enough for some highway cruising. definitely cheaper than a gear vendors. Running a 28" tall rear tire. with 3.23's, I'm not giving up a lot vs 3.91's with GV o/d.

next question is if I have a center section built, do I go with a stock type clutch sure grip or a Tru trac?

 

[Tony Tee]

Differential upgrade YES! Rear disc set up NO!

 

[fesser]

F rear discs then! I'm quite impressionable. She looks restomod but it's a cruiser. 3.91's are the last leftover from a time in my life where I just had to go fast. Already ditched the headers, doublepumper carb. I'm hoping the 3.23's are good enough for some highway cruising. definitely cheaper than a gear vendors. Running a 28" tall rear tire. with 3.23's, I'm not giving up a lot vs 3.91's with GV o/d.

next question is if I have a center section built, do I go with a stock type clutch sure grip or a Tru trac?

Meanwhile, on the opposite side of the country, I am planning to switch from 3.23 to 3.91 with GV overdrive. We are keeping the world balanced.

 

[33 IMP]

I have had good results from factory clutch units. I believe the new clutch units are chinese. The trutrac is American made, and about twice the money. It kinda depends on budget.
Bottom line? If budget allows... trutrac.

 

[Thrashingcows]

F rear discs then! I'm quite impressionable. She looks restomod but it's a cruiser. 3.91's are the last leftover from a time in my life where I just had to go fast. Already ditched the headers, doublepumper carb. I'm hoping the 3.23's are good enough for some highway cruising. definitely cheaper than a gear vendors. Running a 28" tall rear tire. with 3.23's, I'm not giving up a lot vs 3.91's with GV o/d.

next question is if I have a center section built, do I go with a stock type clutch sure grip or a Tru trac?

I've run 3.23's in almost all my mopars over the years and they are a great all around gear, good in town performance but not to high to effect your drivetrain to much while out on the hwy.

As for the sure grip option...I really like the look of the tru-trac system looks like it could handle a ton of power, but since you've "de-tuned" a bit already I don't think you need that option and the clutch style would most likely be more than enough to handle your cars current iteration.

 

[69 GTX]

The only reason I put rear discs on was I am only running 4x26" tires up front and 325/50/15" in back I figured it would take much to lock up the front so I opted for disc brakes where the most rubber was.

 

[Pool Fixer]

Meanwhile, on the opposite side of the country, I am planning to switch from 3.23 to 3.91 with GV overdrive. We are keeping the world balanced.

GV may be in the plans some day... or the silversport 4L60 kit. I'm going to see how it is living with the 3.23's. I've run this car with it's currnet big block on the original 2.94 open diff that was on it from the factory, 3.55 cone type SG with worn out cones, and now tis 3.91 SG that it currently has. I guess it's time to round it out with a set of 3.23's.

still trying to decide to get my OE 2.94 open upgraded locally with new gears and add limited slip or just order a complete one from dr diff or quick performance. OE is a 742 so that's desireable I guess. my 3.91's are a 741 case.

 

[72Dodge]

GV may be in the plans some day... or the silversport 4L60 kit. I'm going to see how it is living with the 3.23's. I've run this car with it's currnet big block on the original 2.94 open diff that was on it from the factory, 3.55 cone type SG with worn out cones, and now tis 3.91 SG that it currently has. I guess it's time to round it out with a set of 3.23's.

still trying to decide to get my OE 2.94 open upgraded locally with new gears and add limited slip or just order a complete one from dr diff or quick performance. OE is a 742 so that's desireable I guess. my 3.91's are a 741 case.

Hi Pool FiXer, I'm on LI too! Any plans on selling the 3.91s when all is said and done? Thanks, Rick

 

[69ChargerR/TSE]

F rear discs then! I'm quite impressionable. She looks restomod but it's a cruiser. 3.91's are the last leftover from a time in my life where I just had to go fast. Already ditched the headers, doublepumper carb. I'm hoping the 3.23's are good enough for some highway cruising. definitely cheaper than a gear vendors. Running a 28" tall rear tire. with 3.23's, I'm not giving up a lot vs 3.91's with GV o/d.

next question is if I have a center section built, do I go with a stock type clutch sure grip or a Tru trac?

Clutch type

 

[dadsbee]

The only reason they put discs on all 4 wheels on modern stuff is because it's cheaper to produce....

My 4 wheel drum cars stop as good, or better, than my front disc rear drum cars. Can't imagine the disappointment with 4 wheel discs. Now if you're gonna road course the car like the bogus Daytona video posted today... go for all wheel disc so you don't overheat things.

 

[Dan64]

True track

 

[Pool Fixer]

Ended up getting the dr diff rear disc kit and a new 3.23 with trutrac from quick performance. brake kit is in my hands, waiting on the diff. It's the American way. why get one when you can get 2 for twice as much? lol

 

[YY1]

Biggest benefit of rear disk brakes?

Much cleaner and easier to change pads than shoes.

Stopping wise, there too little actually done by the rears to notice, although you will surely feel it if they are not right.

 

[Kern Dog]

Adding the Dr Diff rear disc brakes set off a process of chasing perfection that lasted over 16 years. The car just didn’t impress me. I tried numerous changes… multiple manual master cylinders, front caliper sizes, entire front brake swaps, a few power boosters, power master cylinders, proportioning valves and distribution blocks, etc.
Just this year I was able to find a satisfying combination.
My goal was to have the brakes feel and react like a newer car. It sure took a while to get to that point.